I know that 'scat' is the general term, but technically, I've always taken 'scat vocal' as a very specific type of jazz vocalizing (e.g. Ella Fitzgerald, Cab Calloway, etc.), which to my ears and tastes is quite distinct from the dreamy soft-syllable vocalizing heard on pop records, easy listening, lounge, library records, etc. (e.g. Jackie Gleason, Ray Conniff, Anita Kerr, etc.) or film music like Morricone and Edda Dell 'Orso, etc. For years, I've kept an updated playlist of 'wordless' tunes on my players, drawn from every source -- library, lounge, pop, and so on. It's an obsession that goes back more than 20 years now...